Those are very nice bikes. Take note that that's both classic and high end enough that the bike will retain more value in original condition, so I'd advise keeping any modifications reversible, unless you have decided that you primarily want it purely for its rideability. I don't remember offhand which wheel standard that bike would've used--would be either 700c (ISO 622mm) or 27" (ISO 630mm). If it's 700c, that's the more common modern standard and you can really use any modern road tire--Continental 4 Seasons would be my first recommendation for a fast but reasonably puncture resistant tire. For a more vintage look with tan sidewalls, Panaracer Paselas are a good value suggestion, or maybe challenge Strada Bianca for something higher end. If you want to upgrade the wheels, you will run into the problem of the rear frame spacing probably being 120mm, or maybe 126mm, vs the modern 130mm, so you'll have to be more careful sourcing a compatible wheel or get the rear triangle spread and realigned.
If your wheels are currently 27", you can often but not always use a 700c wheel. Can you move your brake pads 4mm down? Then you can use 700c. What's nice is that the slightly smaller wheel coupled with centerpull brakes let you run really pretty wide tires, making for an inexpensive/vintage-ish gravel bike. The same caveat applies to rear hub spacing as above.
They also make the Paselas in 27", which are inexpensive and have a good puncture protection layer, and look really classy with the tan sidewalls.
Easiest reversible upgrades for average riders would be lower gearing--easiest is replacing the freewheel with a wide range freewheel and a cheap modern MTB derailleur and new chain, and you can also replace the crankset with something with lower gearing also, although unfortunately your bike has a French bottom bracket which makes that significantly harder (though not impossible.)